Parker loader control on Jubilee

RandyB(MI)

Well-known Member
The loader settles when levers are in neutral position. Not "fast" but enough to be obnoxious . Question is, do these have "O" rings on the spools or is everything inside just machined to tight tolerances to seal the oil. I can't imagine that but need to know if they actually "wear out" or just need new "O" rings or other check valve seal. Thanks for any help on this. The cylinders are all sealed good with no oil leaks.
 

Something (O-rings or seals) sealing the spools at the outside of the valve body is common. Without the info on the valve I will not say there are no internal seals on spools. I will say it would be highly unusual to have any internal seals, in my experience. Spool/valve body internal sealing fits are commonly a function of machining. That said they can wear and replacement of the entire valve is the normal fix. There may be seals/O-rings on port reliefs or check valves, again detail info on the valve is not available here, and Parker made/makes many different valves. As far as the cylinders not showing leaks, if they are double acting internal leaks, which would allow drifting, can't be seen. I mention this as you didn't say what type they are.
 
Thanks for the info. The large cylinders are single acting but bucket cyl are double. They ALL settle at same rate so valve check is suspect. All functions work perfectly and the "settling" is exactly same amount on BOTH boom and bucket. Gotta think it's a check valve as apposed to spool clearances bypassing. Can't find what I'd call a model # on it.

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On most loader control valves I've seen, there is no single "check valve" that would keep both cylinder circuits in check. It is open center and each spool is its own "check valve" when it is properly centered and is sealing properly.

When you say "They ALL settle at same rate", what are are you using as your measurement? Is it that the rods moved the same number of inches in the same amount of time, or the same percentage of the stroke, or did you calculate the actual amount of fluid that flowed to get them both to move as far as they did?
 
Basically just an eye balling of the "settling". I have it apart and the only thing I can see is even remotely like a "valve" in what I believe is a very stiff spring loaded pressure relief valve. There are no seals,O rings,or anything anywhere else in this valve bank. Nothing to hold pressure on these cylinders accept the fit of machined bore to machined spools. SO, does this mean it's junk? If so, are they re-buildable because one isn't going to find this valve anywhere for sale. OR do I replace it with a modern valve and adapt it ? Did this type valve "ever" seal tight and not settle?
 
(quoted from post at 18:31:21 05/05/20) Basically just an eye balling of the "settling". I have it apart and the only thing I can see is even remotely like a "valve" in what I believe is a very stiff spring loaded pressure relief valve. There are no seals,O rings,or anything anywhere else in this valve bank. Nothing to hold pressure on these cylinders accept the fit of machined bore to machined spools. SO, does this mean it's junk? If so, are they re-buildable because one isn't going to find this valve anywhere for sale. OR do I replace it with a modern valve and adapt it ? Did this type valve "ever" seal tight and not settle?

When it was new it sealed tight, wear from use over the years is showing. One thing you can check is to see that the spools are centering. If a weak spring or adjustment is letting them set off center they will leak by. Yes the internal sealing between the valve body and spools is the fit of the machined spools to each bore. You can buy a new valve for less than you could have the fits of that valve restored to rebuild it. Whether or not it is junk is up to you. If it settles enough to bother you it is "junk". You will need to by a new "modern" valve and retro-fit mounting and plumbing. You will need to be sure the main relief pressure is adjusted to the system pressure called for by your loader. (If you turned the adjustment on your main relief valve you should check and set the pressure if you reuse your current valve.)
 
Thanks Jim and Sean. This is the info I need. This tractor belonged to my uncle and he's 82 and not needing it anymore so a buddy of mine wanting an older low cost loader tractor bought it off him. He test drove it etc but we never stood there and watched to see if loader settled. After he got it home he die. It settles even when running. Told him I'd help and see if we could do anything with it. Personally, I'd just use it, it's a 1953! Ain't gonna be perfect. I'm used to adapting to these things on older stuff but not he I guess. Sounds like modern valve or use it the way it is. Doesn't take that much to remember to check height check before ya take off with it. LOL Thanks again for the help.
 
My guess, probably wear in the spools. I would try taking the valve apart to investigate and clean it good before investing in a new valve. But that's just me. May be just a little contamination keeping the spools a bit out of position in neutral. Some loader controls have a separate relief on the boom circuit that's set lower than the system relief. Shouldn't be difficult for a good carburetor guy.
 
Thanks , Mike. It has just the one relief valve. Disassembled , cleaned and have decided to go back to regular hyd "oil" and use 40 wt as apposed to the modern AW type hyd "fluid" which I'm sure is what's in it. It holds pretty good when cold but not when warm. They didn't have this new "one fluid for whole tractor" stuff back when this was built and I believe this is half the issue. With minimal wear on spools/bore ,and the fact that it hold relatively good when cold , tells me we need to get the "fluid" out and go with non-det straight weight "oil" like it was designed for back then. And we are going with 40 wt as he will not be using it in cold weather. Will let ya know how it turns out. Nothing to lose as he said he isn't buying a new valve and having to re-plumb and also find a valve that will work with the cylinder layout it has. Two boom cyl are single acting but two bucket cyl are double acting. I'm not a hyd xpert but seems it would take some pretty good understanding to get the correct valve and then get it plumbed correctly. Prolly not me.
 
As for your comment "Doesn't take that much to remember to check height check before ya take off with it. LOL". No LOL on that for me. A very basic rule is hydraulic equipment should be lowered to the ground before leaving the seat. (I will add: or blocked so it can't drop.) If he does what he should he would have to pick the bucket off the ground anyway - not just check where it is. If he has to leave it up make stops out of good sized angle iron to set over the lift cylinder rods for the extended length and chain or otherwise secure the bucket. Last thing he wants is a kid or someone hitting a lever and it dropping on someone. Same applies if you have to work under raised equipment.
 
Great point , Jim ! I will bring that up to him as he's threatened to sell this tractor if we can't fix it (without new valve/routing etc) I made him go drive it and use loader and everything before buying it which he did. Also told him it did not have PS so make sure he could handle that. So, he bought it and guy delivered it 20 mi free! Now bitchin' about loader settle and steer hard ? He's on his own from here on out. I guess he "could" go spend $ 40,000 for a new import. Had a hard time even gathering up the $$ for this one. Thanks for all your guys input.
 

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